Conventional cutting tools employ various means for securing cutting inserts to a cutter body. In some cutting tools, threaded bores are provided in the cutter body while corresponding through-bores are provided in the cutting inserts. The cutting inserts are directly secured to the cutter body by using screws. Such a method, however, requires various metal cutting operations to form the thread bores in the cutter body. Also, the threaded bores can weaken the cutter body. Furthermore, when the cutting tool is damaged, a part of the screw that breaks off can fall into the threaded bore of the cutter body.
Other known cutting tools may adopt a structure of securing the cartridge by means of a wedge. For example, U.S. Pat. No. 7,390,150 discloses a cutting tool that includes cutting inserts with wedges and serrations. FIGS. 1 and 2 illustrate a cutting tool according to such prior art. A tool holder body 1 is plate-shaped and comprises a plurality of insert pockets 3, which are arranged at same intervals around the outer circumference. Each of the insert pockets 3 receives a cutting insert 2 and a wedge 4. The top surface of the cutting insert 2 includes serrations 2′. The top surface of the insert pocket 3 includes serrations 3′ corresponding to the serrations 2′ of the cutting insert 2. When the cutting insert 2 is mounted on the insert pocket 3, the serrations 2′ of the cutting insert 2 and the serrations 3′ of the insert pocket 3 engage with each other. The wedge 4 is located under the cutting insert 2 in the insert pocket 3. The screw 5 is fastened into a threaded hole of the insert pocket 3 through a threaded hole of the wedge 4. As the screw 5 advances into the threaded hole of the insert pocket 3, the wedge 4 is pushed toward the threaded hole of the insert pocket 3. Since the wedge 4 tapers inwardly, as the wedge 4 advances toward the threaded hole of the insert pocket 3, the cutting insert 2 is clamped in the insert pocket 3 by the wedge 4.